This invention relates to the preparation of a pure ammonium thioglycolate from thioglycolic acid contaminated with the isopropyl ester of thioglycolic acid. More particularly, it relates to the preparation of a low odor ammonium thioglycolate from thioglycolic acid contaminated with the very odoriferous isopropyl ester of thioglycolic acid by reaction of said acid with aqueous ammonia or ammonium hydroxide at a pH of at least 6.5 to about 9 and an elevated temperature.